Exporting 1 const and 2 funcs

const.go

@@ -4,14 +4,14 @@ const (
 
 	// Icon parameters.
 
-	// Image resolution of the icon
-	// is very small (11x11 pixels), therefore original
-	// image details are lost in downsampling, except
-	// when source images have very low resolution
-	// (e.g. favicons or simple logos). This is useful
-	// from the privacy perspective if you are to use
-	// generated icons in a large searchable database.
-	iconSize = 11
+	// Image resolution of the icon is very small
+	// (11x11 pixels), therefore original image details
+	// are lost in downsampling, except when source images
+	// have very low resolution (e.g. favicons or simple
+	// logos). This is useful from the privacy perspective
+	// if you are to use generated icons in a large searchable
+	// database.
+	IconSize = 11 // Exported to be used in package imagehash.
 	// Resampling rate defines how much information
 	// (how many pixels) from the source image are used
 	// to generate an icon. Too few will produce worse
@@ -30,7 +30,7 @@ const (
 	// Similarity thresholds.
 
 	// Euclidean distance threshold (squared) for Y-channel.
-	thY = float64(iconSize*iconSize) * float64(colorDiff*colorDiff) * euclCoeff
+	thY = float64(IconSize*IconSize) * float64(colorDiff*colorDiff) * euclCoeff
 	// Euclidean distance threshold (squared) for Cb and Cr channels.
 	thCbCr = thY * chanCoeff
 	// Proportion similarity threshold (5%).
@@ -38,8 +38,8 @@ const (
 
 	// Auxiliary constants.
 
-	numPix           = iconSize * iconSize
-	largeIconSize    = iconSize*2 + 1
+	numPix           = IconSize * IconSize
+	largeIconSize    = IconSize*2 + 1
 	resizedImgSize   = largeIconSize * samples
 	invSamplePixels2 = 1 / float64(samples*samples)
 	oneNinth         = 1 / float64(9)

icon.go

@@ -62,7 +62,7 @@ func IconNN(img image.Image) IconT {
 					sumB += b >> 8
 				}
 			}
-			set(largeIcon, largeIconSize, image.Point{x, y},
+			Set(largeIcon, largeIconSize, image.Point{x, y},
 				float64(sumR)*invSamplePixels2,
 				float64(sumG)*invSamplePixels2,
 				float64(sumB)*invSamplePixels2)
@@ -71,7 +71,7 @@ func IconNN(img image.Image) IconT {
 
 	// Box blur filter with resizing to the final icon of smaller size.
 
-	icon := sizedIcon(iconSize)
+	icon := sizedIcon(IconSize)
 	// Pixel positions in the final icon.
 	var xd, yd int
 	var c1, c2, c3, s1, s2, s3 float64
@@ -85,14 +85,14 @@ func IconNN(img image.Image) IconT {
 			for n := -1; n <= 1; n++ {
 				for m := -1; m <= 1; m++ {
 					c1, c2, c3 =
-						get(largeIcon, largeIconSize,
+						Get(largeIcon, largeIconSize,
 							image.Point{x + n, y + m})
 					s1, s2, s3 = s1+c1, s2+c2, s3+c3
 				}
 			}
 			yc, cb, cr = yCbCr(
 				s1*oneNinth, s2*oneNinth, s3*oneNinth)
-			set(icon, iconSize, image.Point{xd, yd},
+			Set(icon, IconSize, image.Point{xd, yd},
 				yc, cb, cr)
 			s1, s2, s3 = 0, 0, 0
 		}
@@ -106,7 +106,7 @@ func IconNN(img image.Image) IconT {
 // with nil values, for example for convenient error handling.
 // Then you can use icon.Pixels == nil condition.
 func EmptyIcon() (icon IconT) {
-	icon = sizedIcon(iconSize)
+	icon = sizedIcon(IconSize)
 	icon.Pixels = nil
 	return icon
 }
@@ -125,7 +125,8 @@ func arrIndex(p image.Point, size, ch int) (index int) {
 // Set places pixel values in an icon at a point.
 // c1, c2, c3 are color values for each channel
 // (RGB for example). Size is icon size.
-func set(icon IconT, size int, p image.Point, c1, c2, c3 float64) {
+// Exported to be used in package imagehash.
+func Set(icon IconT, size int, p image.Point, c1, c2, c3 float64) {
 	// Multiplication by 255 is basically encoding float64 as uint16.
 	icon.Pixels[arrIndex(p, size, 0)] = uint16(c1 * 255)
 	icon.Pixels[arrIndex(p, size, 1)] = uint16(c2 * 255)
@@ -135,7 +136,8 @@ func set(icon IconT, size int, p image.Point, c1, c2, c3 float64) {
 // Get reads pixel values in an icon at a point.
 // c1, c2, c3 are color values for each channel
 // (RGB for example).
-func get(icon IconT, size int, p image.Point) (c1, c2, c3 float64) {
+// Exported to be used in package imagehash.
+func Get(icon IconT, size int, p image.Point) (c1, c2, c3 float64) {
 	// Division by 255 is basically decoding uint16 into float64.
 	c1 = float64(icon.Pixels[arrIndex(p, size, 0)]) * one255th
 	c2 = float64(icon.Pixels[arrIndex(p, size, 1)]) * one255th
@@ -224,7 +226,7 @@ func (icon IconT) ToRGBA(size int) *image.RGBA {
 	img := image.NewRGBA(image.Rect(0, 0, size, size))
 	for x := 0; x < size; x++ {
 		for y := 0; y < size; y++ {
-			r, g, b := get(icon, size, image.Point{x, y})
+			r, g, b := Get(icon, size, image.Point{x, y})
 			img.Set(x, y,
 				color.RGBA{uint8(r), uint8(g), uint8(b), 255})
 		}

icon_test.go

@@ -59,7 +59,7 @@ func TestArrIndex(t *testing.T) {
 
 func TestSet(t *testing.T) {
 	icon := sizedIcon(4)
-	set(icon, 4, image.Point{1, 1}, 13.5, 29.9, 95.9)
+	Set(icon, 4, image.Point{1, 1}, 13.5, 29.9, 95.9)
 	expected := sizedIcon(4)
 	expectedPixels := []float64{0, 0, 0, 0, 0, 13.5, 0, 0, 0, 0, 0,
 		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 29.9, 0, 0, 0, 0,
@@ -82,7 +82,7 @@ func TestGet(t *testing.T) {
 	for i := range iconPix {
 		icon.Pixels[i] = uint16(iconPix[i] * 255)
 	}
-	c1, c2, c3 := get(icon, 4, image.Point{1, 1})
+	c1, c2, c3 := Get(icon, 4, image.Point{1, 1})
 	if math.Abs(float64(c1)-13.5) > 0.1 || math.Abs(float64(c2)-29.9) > 0.1 || math.Abs(float64(c3)-95.9) > 0.1 {
 		t.Errorf(
 			"Expected near 13.5, 29.9, 95.9, got %v, %v, %v.",